Kiva provides an excellent way for people to engage in peer-to-peer lending by providing microloans to small entrepreneurs in poor countries (and now in the U.S. as well). However, how do you find funding for larger projects that require greater amounts of capital? One option is an organization like Root Capital, which is run by a social entrepreneur named William Foote.
I had never heard of Root Capital until recently when they won the 2009 Financial Times Sustainable Banking Award. According to their website, they deal specifically with rural entrepreneurs, and focus on filling the gap for loans that are too big for microfinance and too small (and risky) for mainstream banks. (Though I think I could make an argument that our mainstream banks took plenty of risks in the last decade.) Still, it's interesting to see more segments of the market being served by investment.